1. Field of the Invention
The invention relates to a manipulator, in particular for positioning a test head on a tester, comprising a positioning means by which the test head is three-dimensionally positionable. The manipulator features furthermore a cradle to which the test head is securable and which is connected to the positioning means. The invention furthermore relates to a compensator for application with one such manipulator and serving to compensate the mass of the test head.
A manipulator for positioning a test head normally has a plurality of translational and rotational degrees of freedom which allow for the test head to be precisely positioned three-dimensionally and to be positioned at a desired location. This is why, as a rule, such a manipulator finds application in testing electronic components such as, for instance, integrated circuits (ICs) or wafers. For function or quality testing electronic components it is necessary to precisely locate the relatively heavy test head at a tester. The tester, for example as a device handler or wafer prober, presents the electronic components to the test head for testing. Obtaining a genuine test result when testing electronic components requires precise docking of the test head at the tester. This is why precise, smooth adjustment of the manipulator positioning the test head is a mandatory requirement.
2. Description of Related Art
Smooth adjustment of the test head is obtained when the manipulator is provided with a compensator which compensates the mass of the test head. The compensator relieving the positioning means of the weight of the test head usually features a counterweight connected to the test head. Manipulators in which the mass of the test head is compensated by a counterweight are described, for instance, in German patents DE 36 17 741 C2 and DE 40 07 011 C2.
In addition German patent DE 10 2004 026 031 B3 discloses a manipulator permitting temporary loading of the test head to be docked on a tester to achieve reliable contacting of the tester. A manipulator provided with a fixed counterweight is described in U.S. Pat. No. 6,766,996 B1.